A five-star hotel and casino. Well thanks, Kevin

Today, a "spiritual gathering" takes place on a tract of land in the Black Hills of South Dakota. Hundreds, perhaps thousands, will converge on the site where film star Kevin Costner and his brother Dan are building a 320-room luxury hotel-casino complex. Most of the protestors will be Lakota Sioux Indians, who claim that Costner is building on land that belongs to them.

Standing at the centre of a six-state area once known to white settlers as "Indian country", the Black Hills, or Paha Sapa, are sacred to the Sioux. These were their burial grounds and holy lands, where they came on "vision quests", and held their annual Sundance rituals. Only 150 years ago they lived a semi-nomadic existence, here on the Great Plains.

But once settlers discovered gold in the hills, the US government systematically persecuted the Indians to the edge of extinction, herded them on to reservations that were little more than concentration camps, and did its best to annihilate their language and culture. The Black Hills were sold off to property developers, gold and mineral mining companies, and timber firms. Anything left over was declared National Forest land, and the Indians were denied access for religious ceremonies.

Now, Kevin Costner is hoping to attract thousands of European and Japanese tourists with a five-star monument to kitsch called The Dunbar. The long- suffering Sioux regard this as the last straw, and plan to occupy the land today in order to make a peaceful protest.

The bitter irony here, of course, is that Costner built his Hollywood career on the back of Sioux culture. In his 1990 film Dances With Wolves, Costner played Lt John Dunbar, an 1860s cavalryman who becomes enchanted with the Lakota way of life and "goes native". Dances with Wolves made more than $500m worldwide, and Costner, as director, producer and star, took about 10 per cent of that sum.

And how did he repay the Indians whose culture, language and history he had employed so freely? Did he build a hospital on one of South Dakota's four reservations? Did he set up a college trust fund to educate underprivileged Indian kids? Did he buy a piece of the Black Hills and give it back to the Sioux, so that they could perform their religious ceremonies there?

Well, no actually. Despite the unthinkable wealth generated by Dances, and the fact that South Dakota's Indians are, according to the latest US government census, the poorest people in the entire United States, nobody can recall Costner donating so much as a dollar to an Indian cause. Perhaps he thinks they should be grateful that he is investing $100m in the Dunbar resort (where they can apply for minimum-wage jobs, washing dishes and the like). But nobody really knows what he thinks, because Costner refuses to discuss the matter.

Of course, Kevin Costner can produce deeds of ownership for the land. But so can the Sioux, whose papers date from 1851, when the first Fort Laramie Treaty was signed with the US government, acknowledging the Indians' ownership of 60 million acres of the Great Plains, including the 7.3 million acres of the Black Hills. In 1868 a second treaty was drawn up, reducing the Indian land to 26 million acres, but still including the area now being developed by Costner.

There is also the small matter of 1980's US Supreme Court ruling, which declared the Lakota Sioux the rightful owners of the Black Hills, and denounced the government's appropriation as a "rank case of dishonourable dealings ... unparalleled in American jurisprudence". (The Sioux, however, rejected the Court's award of $105m as "insulting". You can see their point: the hills have yielded over $250bn of gold alone in the last 100 years.)

"I believe the Dunbar resort is not only illegal, because the Black Hills issue remains unresolved," says Mitchell Zephier, a Lakota Sioux jeweller, "but it comes down to whether or not we hold the earth to be sacred. And the earth is sacred, you know, it's a gift to all of us. It's not about material gain. It's about sustaining life, and life itself is sacred."

Costner's PR people say he "wants to leave a legacy" in the Black Hills. But what kind? He can bequeath yet another symbol of avarice and deceit, a luxury palace for the privileged classes. Or he could still rebuild bridges with the Lakota (who even now are unwilling to condemn him) and put something back into the land from which he already taken so much. Just a fraction of his casino budget could establish sustainable subsistence farming on the reservations, for example,

Maybe Kevin Costner will realise that this debate goes much deeper than the argument about his casino,. It extends beyond the Black Hills, and has significance for all of us, touching on the very nature of our relationship with the earth. It begs the question of whether we are prepared to recognise and maintain the sacred nature of the land, or if indeed we agree that everything has its price, and anything can be bought and sold.